Program.cs

 using System.Text.RegularExpressions;

var pRequirement = new PasswordRequirement(8, true, true, true, true);
 
 
  var results = ValidatePasswordRequirement(testPassword,pRequirement);

  Console.WriteLine(!results.Item1 ? results.Item2 : "Password is valid");
 
 (bool, string) ValidatePasswordRequirement(string password, PasswordRequirement passwordRequirement)
        {
            
            //1. checks the value
            if (string.IsNullOrEmpty(password))
            {
                return (false, "The password cannot be empty");
            }

            //2. Validate minimum length
            if (password.Length < passwordRequirement.MinimumLength)
            {
               return (false ,$"The password must be over {passwordRequirement.MinimumLength} characters.");
            }

            //3. At least one lowercase character
            if (passwordRequirement.RequireLowercase)
            {
                Match lowercase = Regex.Match(password, @"^(?=.*[a-z])");
                if (!lowercase.Success)
                {
                    return (false ,"The password must contain at least one lowercase character.");
                }
            }

            //4.  At least one upper case character
            if (passwordRequirement.RequireUppercase)
            {
                Match uppercase = Regex.Match(password, @"^(?=.*[A-Z])");
                if (!uppercase.Success)
                {
                    return (false ,"The password must contain at least one uppercase character.");
                }
            }

            // 3. At least one digit
            if (passwordRequirement.RequireDigit)
            {
                Match digit = Regex.Match(password, @"^(?=.*\d)");
                if (!digit.Success)
                {
                    return (false ,"The password must contain at least one digit.");
                }
            }

            // 4. At least one special character
            if (passwordRequirement.RequireNonAlphanumeric)
            {
                Match specialCharacter = Regex.Match(password, @"^(?=.*[^\da-zA-Z])");
                if (!specialCharacter.Success)
                {
                    return (false ,"The password must contain at least one non-alphanumeric character.");
                }
            }

            
            return (true, "Password is valid");
        }
    
}

public record PasswordRequirement(
    int MinimumLength,
    bool RequireUppercase,
    bool RequireLowercase,
    bool RequireNonAlphanumeric,
    bool RequireDigit
);